The proposed study involves the use of the accessory olfactory system (AOS) and its processing of pheromonal stimuli as a model system within which to investigate the role of spatial organization in the function of the nervous system. The key question for any sensory system is the physiological mechanisms underlying signal detection, encoding and processing. The AOS represents one of the two main components of the olfactory Systems. It seems to specialize in the detection and processing of sexually relevant signals and the transmission of these signals to other brain areas, several of which are important for modulating reproductive function. The present study aims to investigate the role of spatial organization in pheromonal reception in the VNO and the spatial nature of the projection from the VNO to AO using both electrical and chemical stimulation, and electrophysiological recording techniques. In addition, since sexual experience seems to determine the relative importance of VNO input, parallel experiments will be carried out in experienced and inexperienced males. The present studies will fill in some of the gaps in our knowledge of sensory information processing in the olfactory system.